1. Technical Field
The present disclosure relates to a Liquid Crystal Display (LCD), and more particularly, to a method of reducing errors in images displayed on the LCD due to external noise, and a LCD drive integrated circuit (IC) for performing the same.
2. Discussion of the Related Art
FIG. 1 is a block diagram of a conventional LCD drive integrated circuit (IC). Referring to FIG. 1, the conventional LCD drive IC includes a graphic RAM (GRAM) 160, a source driver 170, a gate driver 180, a controller 150, and a timing controller 140. The GRAM 160 stores image data transmitted from a host 110. The source driver 170 receives the image data from the GRAM 160 and transmits the data to source lines of a LCD panel 190. The gate driver 180 drives gate lines of the LCD panel 190 on which the image data is displayed. The controller 150 controls input and output of the image from the GRAM 160. The timing controller 140 receives a clock signal from an oscillator 130 and supplies the clock signal adjusted to the controller 150.
When an image is displayed on the LCD panel 190, the controller 150 stores frames of the corresponding image data in the GRAM 160. The image data is transmitted by the host 100. For example, when the LCD panel 190 has a pixel resolution of 240×320, and if a pixel represents 18 bits, nearly 1.4 million bits (i.e., 1,382,400=240×320×18 bits) are stored for each frame of the image by the controller 150 in the GRAM 160. The controller 150 controls the GRAM 160 and the gate driver 180 simultaneously, so that image data corresponding to a horizontal line of the LCD panel 190 is outputted to the source driver 170 from the GRAM 160 and a scan pulse corresponding to the horizontal line address is outputted from the gate driver 180, respectively.
The gate driver 180 outputs the scan pulse to the LCD panel 190 and then the source driver 170 outputs the image data to the source line of the LCD panel 190. Such operations are repeatedly performed until image data of one frame is outputted to the LCD panel 190.
In addition, while not illustrated in FIG. 1 in detail, the LCD drive IC includes a plurality of controllers. The controllers can control modules of the LCD drive IC and may include, for example, a GRAM controller, a timing controller, and a gate driver controller. The controllers are electrically connected to a control register. The control register stores commands that correspond to each of the controllers.
FIG. 2 is a diagram schematically illustrating that an electrostatic discharge (ESD) can change data values stored in a control register. The control register includes a flipflop 210, which outputs values stored by a command to a logic circuit 220. The values are command data, and may include, for example, bit values for setting common voltage, bit values for gamma correction, etc.
However, when the LCD drive IC is exposed to external noise such as, electrostatic discharge (ESD) or electromagnetic interference (EMI) while displaying images, the values stored in the control register may change. The changed values may cause a malfunction of the internal logic circuit 220, resulting in the display of abnormal images on the LCD screen.
A method of periodically refreshing bit values stored in the control register by an outside host chip has been used to improve the quality of the displayed image. However, when such a method is used, the life span of the outside host chip is shortened and power consumption is increased for mobile TFT display devices such as, Mobile Phones, Smart Phones, and Portable Media Players.
Thus, there is a need for a method of recovering bits of a control register in a LCD drive IC that does not rely on an outside host, and a LCD drive IC performing the same.